During his spare time, he played in a band, and soon became a professional musician earning £4 a week.[1] The band appeared on the BBC Light Programme, but Hazlehurst left when he was refused a pay rise.[1] Moving to Manchester, he became a freelance musician until he was offered a place in another band at a nightclub in London.[1] Ronnie Hazlehurst worked at Granada for about a year in 1955 and, after he left there, worked on a market stall in Watford to make ends meet.[1][2]

His theme tunes often included elements designed to fit the programmes, such as a cash till in Are You Being Served?, rises and falls in The Fall and Rise of Reginald Perrin and the Big Ben chimes for Yes Minister.[1][2] For Some Mothers Do 'Ave 'Em, Hazlehurst used Morse code to spell out the programme's title.[4][6] During his BBC career he composed the music for the opening of the BBC's coverage of the 1976 Olympics.[1] He left the BBC in the 1990s.[2]

Hazlehurst moved from Hendon, North London, to Guernsey in about 1997.[4] In 1999, he was awarded a Gold Badge from the British Academy of Composers and Songwriters.[4]

Music was Hazlehurst’s life and passion as well as his work and he continued to work right up to his heart bypass operation in October 2006.[4] On 27 September 2007 he suffered a stroke and, without regaining consciousness, died on 1 October in Princess Elizabeth Hospital, St Martin, Guernsey.[5][8] Having been married twice, with two sons from his second marriage, at the time of his death his partner was Jean Fitzgerald.[4]